1. Field of the Invention
The present invention relates to apparatus for dispensing viscous fluids such as plastisol inks.
2. Description of the Prior Art
Viscous fluids are commonly used in many commercial applications. Examples of such fluids include thermoplastic materials, lubricants and inks such as plastisol ink. Such fluids are, however, quite difficult to work with due to problems associated with pouring and handling. In the case of plastisol inks, for example, the fluid is very viscous and does not pour easily. Furthermore, the inks will adhere, or stick, to most surfaces.
Attempts at dispensing materials such as plastisol inks quite often result in many complications. Firstly, the inks are normally purchased in containers such as buckets etc. In order to dispense the material in an automated manner, the containers must usually be emptied into a hopper or the like of a dispensing apparatus. Such transfer is associated with problems due to the xe2x80x9cstickyxe2x80x9d nature of the material. For example, due to the high cost of plastisol inks, the buckets of material must usually be scraped to minimize loss of material. Further, due to the highly viscous nature of plastisol inks, most pumping systems usually result in inconsistent spurting of the material.
Various dispensing systems for viscous fluids have been provided in the prior art. Examples of such systems include those taught in U.S. Pat. Nos. 4,635,820; 4,790,456; 5,170,710; and, 5,275,100. However, the known devices have various deficiencies. For example, in some cases, the viscous fluid requires transfer from its original container into a holding container. Such transfer, as discussed above, is quite difficult and often results in loss of material. In addition, the known devices often include complex pumping systems to handle the highly viscous nature of the fluid.
Thus, a need exists for a dispenser for viscous fluids, particularly plastisol inks, that overcomes the deficiencies inherent with the known devices.
In accordance with one embodiment, the present invention provides an apparatus for dispensing a viscous fluid, such as plastisol ink, from a generally cylindrical container containing such fluid, the apparatus comprising:
a frame including a base for supporting the container, and a platform, generally vertically separated from the base, for supporting a plunger mechanism;
the plunger mechanism including a plunger and a drive mechanism for advancing the plunger towards the container and for impinging on the fluid;
the plunger being adapted to sealingly engage the interior wall of the container; and,
the plunger including an exit port there-through for allowing ejection of the fluid from the container as the plunger is advanced into the container.
In another embodiment, the present invention provides an apparatus for dispensing a viscous fluid, such as plastisol ink, from a generally cylindrical container containing such fluid, the apparatus comprising:
a frame including a base for supporting the container, and a platform, generally vertically separated from the base, for supporting a plunger mechanism;
the plunger mechanism including a plunger and a drive mechanism for advancing the plunger towards the container and for impinging on the fluid;
the plunger being adapted to sealingly engage the interior wall of the container; and,
the plunger including an exit port there-through for allowing ejection of the fluid from the container as the plunger is advanced into the container;
wherein the drive mechanism includes one or more advancing arms each having first and second ends, the first ends being attached to the plunger and the second ends being attached to an advancing mechanism and wherein the advancing mechanism includes:
a threaded screw rod, secured in a generally vertical position to the frame and being rotatable about its central axis;
a nut having a correspondingly threaded aperture for engaging the screw rod and being capable of traversing along the length of the screw rod as the screw rod is rotated;
the nut being attached to the second ends of the advancing arms;
and a motor for rotating the screw rod;
whereby as the screw rod is rotated by the motor, the nut is raised or lowered.
In yet another embodiment, the invention provides an apparatus for dispensing a viscous fluid, such as a plastisol ink, from a generally cylindrical container containing such fluid, the apparatus comprising:
a frame means for supporting the container;
a plunger means, supported on the frame means, for applying pressure to the fluid in the container for forcing the fluid out of the container and through a port in the plunger means;
a drive means, supported on the frame means, for advancing the plunger means.
In yet another embodiment, the invention provides a system for dispensing a viscous fluid, such as plastisol ink, from a cylindrical container comprising a plurality of dispensing devices, each of the dispensing devices comprising:
a frame including a base for supporting the container, and a platform, generally vertically separated from the base, for supporting a plunger mechanism;
the plunger mechanism including a plunger and a drive mechanism for advancing the plunger towards the container and for impinging on the fluid;
the plunger being adapted to sealingly engage the interior wall of the container; and,
the plunger including an exit port there-through for allowing ejection of the fluid from the container as the plunger is advanced into the container.
In another embodiment, the invention provides a plunger for use in dispensing a viscous fluid, such as plastisol ink, from a bucket, the plunger including:
a generally central exit port;
a funnel portion having a concave fluid contacting surface for directing the fluid to the exit port;
and an outer edge for sealingly engaging the interior walls of the bucket;
whereby, as the plunger is advanced into the bucket, the fluid is forced through the exit port.